SI-7325 cleans up corner cases of percent handling in StringContext.f

See comments in code for the exhaustive list of the cases handled.
Also note that treatment of non-formatting percents has been changed.
Embedding literal %'s now requires escaping.

Moreover, this commit also features exact error positions for string
interpolation, something that has been impossible until the fix for
SI-7271, also included in this patch.

7 files changed, 91 insertions, 3 deletions

diff --git a/test/files/neg/stringinterpolation_macro-neg.check b/test/files/neg/stringinterpolation_macro-neg.check
index 8986b899a3..457f497f2f 100644
--- a/test/files/neg/stringinterpolation_macro-neg.check
+++ b/test/files/neg/stringinterpolation_macro-neg.check
@@ -66,5 +66,5 @@ Note that implicit conversions are not applicable because they are ambiguous:
        ^
 stringinterpolation_macro-neg.scala:30: error: illegal conversion character
   f"$s%i"
-     ^
+       ^
 15 errors found
diff --git a/test/files/neg/t7325.check b/test/files/neg/t7325.check
new file mode 100644
index 0000000000..709ab6db3e
--- /dev/null
+++ b/test/files/neg/t7325.check
@@ -0,0 +1,19 @@
+t7325.scala:2: error: percent signs not directly following splicees must be escaped
+  println(f"%")
+            ^
+t7325.scala:4: error: percent signs not directly following splicees must be escaped
+  println(f"%%%")
+              ^
+t7325.scala:6: error: percent signs not directly following splicees must be escaped
+  println(f"%%%%%")
+                ^
+t7325.scala:16: error: wrong conversion string
+  println(f"${0}%")
+                ^
+t7325.scala:19: error: percent signs not directly following splicees must be escaped
+  println(f"${0}%%%d")
+                  ^
+t7325.scala:21: error: percent signs not directly following splicees must be escaped
+  println(f"${0}%%%%%d")
+                    ^
+6 errors found
diff --git a/test/files/neg/t7325.scala b/test/files/neg/t7325.scala
new file mode 100644
index 0000000000..adfd8dd47a
--- /dev/null
+++ b/test/files/neg/t7325.scala
@@ -0,0 +1,25 @@
+object Test extends App {
+  println(f"%")
+  println(f"%%")
+  println(f"%%%")
+  println(f"%%%%")
+  println(f"%%%%%")
+  println(f"%%%%%%")
+
+  println(f"%%n")
+  println(f"%%%n")
+  println(f"%%%%n")
+  println(f"%%%%%n")
+  println(f"%%%%%%n")
+  println(f"%%%%%%%n")
+
+  println(f"${0}%")
+  println(f"${0}%d")
+  println(f"${0}%%d")
+  println(f"${0}%%%d")
+  println(f"${0}%%%%d")
+  println(f"${0}%%%%%d")
+
+  println(f"${0}%n")
+  println(f"${0}%d%n")
+}
\ No newline at end of file
diff --git a/test/files/run/interpolation.scala b/test/files/run/interpolation.scala
index f443bd5feb..14d9819348 100644
--- a/test/files/run/interpolation.scala
+++ b/test/files/run/interpolation.scala
@@ -13,7 +13,7 @@ object Test extends App {
     println(s"Best price: $f")
     println(f"Best price: $f%.2f")
     println(s"$f% discount included")
-    println(f"$f%3.2f% discount included")
+    println(f"$f%3.2f%% discount included")
   }
 
   test1(1)
diff --git a/test/files/run/interpolationMultiline1.scala b/test/files/run/interpolationMultiline1.scala
index 437aed44b0..db634e7775 100644
--- a/test/files/run/interpolationMultiline1.scala
+++ b/test/files/run/interpolationMultiline1.scala
@@ -13,7 +13,7 @@ object Test extends App {
     println(s"""Best price: $f""")
     println(f"""Best price: $f%.2f""")
     println(s"""$f% discount included""")
-    println(f"""$f%3.2f% discount included""")
+    println(f"""$f%3.2f%% discount included""")
   }
 
   test1(1)
diff --git a/test/files/run/t7325.check b/test/files/run/t7325.check
new file mode 100644
index 0000000000..3c7652f42c
--- /dev/null
+++ b/test/files/run/t7325.check
@@ -0,0 +1,19 @@
+%
+%%
+%%%
+%n
+%
+
+%%n
+%%
+
+%%%n
+%%%
+
+0
+0%d
+0%%d
+0
+
+0
+
diff --git a/test/files/run/t7325.scala b/test/files/run/t7325.scala
new file mode 100644
index 0000000000..26f6bc6ef7
--- /dev/null
+++ b/test/files/run/t7325.scala
@@ -0,0 +1,25 @@
+object Test extends App {
+  // println(f"%")
+  println(f"%%")
+  // println(f"%%%")
+  println(f"%%%%")
+  // println(f"%%%%%")
+  println(f"%%%%%%")
+
+  println(f"%%n")
+  println(f"%%%n")
+  println(f"%%%%n")
+  println(f"%%%%%n")
+  println(f"%%%%%%n")
+  println(f"%%%%%%%n")
+
+  // println(f"${0}%")
+  println(f"${0}%d")
+  println(f"${0}%%d")
+  // println(f"${0}%%%d")
+  println(f"${0}%%%%d")
+  // println(f"${0}%%%%%d")
+
+  println(f"${0}%n")
+  println(f"${0}%d%n")
+}
\ No newline at end of file